The long-range objective of the proposal is to develop plasma membrane modifiers and inhibitors affecting the viability and social behavior of the cancer cells and hopefully increasing their immunogenicity and permeability with respect to anti-cancer drugs. The following approaches will be pursued: (a) Synthesis of D-mannosamine and sialic acid analogs to inhibit specifically sialic acid biosynthesis and its transfer to the glycoconjugate, (b) Synthesis of D-galactosamine analogs, (c) Synthesis of D-glucosamine analogs modified in the 3 and 4 positions, (d) Exploration of membrane sugar esters as prodrugs, (e) Hexokinases as an in vitro test system, (f) Biological evaluation of metabolic and specific membrane effects of carbohydrate analogs.